Apparatuses used in a domestic environment are normally powered using AC voltage (110V-240V; 50-60 Hz) and if needed connected to a separate communication network. Some domestic apparatuses are powered using DC voltage, which normally is provided by converting AC voltage (VAC) to a suitable DC-voltage (VDC). In order to simplify power distribution, separate feed cables for VDC and VAC have been proposed.
U.S Pat. No. 5,003,112 assigned to Northern Telecom Limited, discloses a closed loop, programmable power and communication system, in which feed cables for VAC and VDC are provided together with a separate cable for data communication purposes. The incoming VAC is converted to a 48 VDC and a cable bundle including AC and DC power distribution as well as data communication is wired throughout a building.
The system disclosed in U.S. Pat. No. 5,003,112 is briefly described in connection with FIG. 1 , in which the traditional wiring of a power distribution network is used, such as arranging a switch on the data feed cable for the purpose of controlling a lamp connected to a power outlet, see switch 18 and the lamp 17 in FIG. 1.
It has also been proposed to distribute VDC within a Local Area Network using a twisted pair network with a superimposed data communication channel.
U.S. Pat. No. 7,424,031, assigned to Serconet Ltd, discloses a combined VDC and data communication over a twisted pair cable in a local area network (LAN). existing telephone wiring, or electrical wiring, in a building may be used to create the LAN. The data communication signal may be implemented as a superimposed signal over the DC voltage, as disclosed in US 2003/0036819, paragraph [0048].
Although power distribution and communication has been implemented over a two-wire network, such as a twisted pair cable, there still exists a need to further simplify wiring of different units in such a network.